The "skylight" is just a small glass face, and was abbreviated "Lt" on the plan.

Modeller Tone Source Shipyard Plans for HMS Acheron (1911) from the National Maritime Museum Grid Size 1 mm Scale 1/48 This fitting could doubtless be improved. It is difficult to tell if all fittings of the same size/function would be of the exact same design. Perhaps some rivets on the bottom sealing ring would be good, but I omitted them for simplicity and since I did not know a good shape or count for them. I think the ring around the glass might better be stainless steel or brass. This item would likely be painted steel, but that is Tone's guess.

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